Impact of human bladder cancer cell architecture on autologous T-lymphocyte activation

To investigate the influence of tumor cell architecture on T-cell activation, we used an autologous human model based on 2 bladder tumor cell lines as targets for cytotoxic tumor-infiltrating lymphocytes (TILs). These tumor cell lines were grown in vitro as either standard 2-dimensional (2D) monolayers or 3-dimensional (3D) spheroids. T-cell activation was determined by measuring the production of three major cytokines (tumor necrosis factor, granulocyte/macrophage colony-stimulating factor and interferon-gamma), known to be secreted by most activated TILs. Changes in the architecture of target cells from 2D to 3D induced a dramatic decrease in their capacity for stimulating TILs. Interestingly, neither TIL infiltration nor MHC class I, B7.1 costimulatory or lymphocyte function-associated factor-3 adhesion molecule downregulation played a major role in this decrease. These findings demonstrate that tumor architecture has a major impact on T-cell activation and might be implicated in the escape of tumor cells from the immune system

Tumor-associated antigen human chorionic gonadotropin beta contains numerous antigenic determinants recognized by in vitro-induced CD8+ and CD4+ T lymphocytes.

The beta subunit of human chorionic gonadotropin (hCG beta) is markedly overexpressed by neoplastic cells of differing histological origin including those present in colon, breast, prostate and bladder tumors. We have previously shown that some patients with hCG beta-producing urothelial tumors have circulating T cells that proliferate in response to hCG beta. To make a comprehensive study of hCG beta as a potential target for cancer immunotherapy, we investigated whether hCG beta peptides could induce CD4+ or CD8+ T-cell responses in vitro. By stimulating peripheral blood mononuclear cells (PBMCs) from three donors with mixtures of overlapping 16-mer synthetic peptides analogous to portions of either the hCG beta 20-71 or the hCG beta 102-129 region, we established six CD4+ T-cell lines that proliferated specifically in response to five distinct determinants located within these two hCG beta regions. Three antigenic determinants (hCG beta 52-67, 106-121 and 114-125) were presented by HLA-DR molecules, while the two other antigenic determinants (hCG beta 48-63 and 56-67) were presented by HLA-DQ molecules. Interestingly, one T-cell line specific for peptide hCG beta 106-121 recognized hCG beta peptides comprising, at position 117, either an alanine or an aspartic acid residue, with the latter residue being present within the protein expressed by some tumor cells. In addition, three other hCG beta-derived peptides that exhibited HLA-A*0201 binding ability were able to stimulate CD8+ cytotoxic T cells from two HLA-A*0201 donors. These three immunogenic peptides corresponded to regions hCG beta 40-48, hCG beta 44-52 and hCG beta 75-84. Our results indicate that the tumor-associated antigen hCG beta possesses numerous antigenic determinants liable to stimulate CD4+ and CD8+ T lymphocytes, and might thus be an effective target antigen for the immunotherapy of hCG beta-producing tumors

Régulation de la réponse immunitaire par les molécules HLA

International audienc

Preferential usage of the T-cell receptor by influenza virus hemagglutinin-specific human CD4+ T lymphocytes: in vitro life span of clonotypic T cells

Human helper T-cell (Th) responses to influenza A virus were studied by analyzing T-cell receptor V beta gene diversity in hemagglutinin-specific Th lymphocytes. The T-lymphocyte population from peripheral blood became quickly oligoclonal when stimulated in vitro with the HA306-329 peptide, and T-cell receptor V beta 3 genes were mainly expanded. Moreover, specific junctional region oligonucleotide probes corresponding to hemagglutinin-specific clones were used to estimate temporal diversity during antigenic stimulations.</jats:p

Implication of HLA-DR residues at positions 67, 71, and 86 in interaction between HLA-DR11 and peptide HA306-320.

Abstract To get further insight into the role of three polymorphic DR residues located in one alpha-helix of the HLA-DR binding groove, we studied how natural substitutions at positions 67, 71, and 86 on DR11 molecules influence MHC binding and/or T cell recognition of peptide HA306-320 and of monosubstituted peptide analogues. Our results show that: 1) Reactivities of all HA306-320-specific T cell clones tested are decreased by DR substitution at position 86 and can even be lowered by additional substitutions at position 71, and at positions 71 plus 67, indicating that these three residues are functionally important. 2) The functional effects of substitutions at positions 67, 71, and/or 86 cannot be explained by a decreased affinity of HA306-320 for the substituted DR11 molecules, as determined in binding assays. 3) More likely, they are explained by modifications of the conformation, orientation, or location of the peptide once bound in the HLA groove, because each individual DR substitution at positions 86, 71, and 67 differentially affects the binding ability of the same panel of 50 monosubstituted analogues. 4) This interpretation is reinforced by the identification of a small set of monosubstituted analogues that can compensate the functional effects of DR substitutions at positions 86, 86 plus 71, or 86 plus 71 plus 67, and thus restore T cell reactivities. All together these results strongly suggest that residues 67, 71, and 86 play a key role in interactions with HA306-320, probably by modifying the way the peptide is bound within the binding groove of HLA-DR11. Using the same DR11.1-restricted clones, we identified putative T cell and DR contact residues of HA306-320 by comparing DR binding and T cell-activating capacity of the peptide analogues. This analysis suggests that: 1) Residues 310, 311, 312, 313, and 316 are putative TCR contacts. 2) Peptide HA306-320 anchors to DR11.1 molecules mainly via residue Y-309, possibly at the vicinity of DR residue 86, whereas peptide residues 315 and 317 constitute minor aggregotopes that would be at the vicinity of DR residues 71 and/or 67. 3) Finally, residues 308, 310, and 314 might also be on the MHC side of the DR-peptide-TCR complex.</jats:p